CSX and Berkshire Hathaway-owned BNSF on Friday announced new coast-to-coast services, a move that strengthens their freight connectivity but that tempers market expectations of an imminent merger between the two rail giants.

CSX may also be responding to activist pressure, the TD Cowen analysts said. Ancora Holdings has been pushing CSX to either pursue a deal with a rival or replace its chief executive, The Wall Street Journal reported this month.

A partnership between CSX Corp. (CSX) and Berkshire Hathaways' (BRK.B) BNSF isn't a replacement for an eventual combination of the two railroads, according to an Evercore ISI analyst.